pig错误：无法找到或加载主类org.apache.pig.main

wz3gfoph 于 2021-05-30 发布在 Hadoop

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我是Pig的初学者。
我在wiki之后编写了一个程序，将文件中的单词转换为大写。
--cat上限.java

package com.bigdata.myUdf;

import java.io.IOException;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.util.WrappedIOException;

public class UPPER extends EvalFunc<String> {

public String exec(Tuple input) throws IOException {
    if (input == null || input.size() == 0)
    return null;
    try{
    String str = (String)input.get(0);
    return str.toUpperCase();
    }catch(Exception e){
    throw WrappedIOException.wrap("Caught exception processing input row ", e);
    }
    }

}

--cat/home/hduser/lab/mydata/myscript.pig

REGISTER /home/hduser/software/myUdfs/UPPER.jar
std_det = LOAD '/pigdata/udf1.txt' USING PigStorage(',') as (name:chararray);
B = FOREACH std_det GENERATE com.bigdata.myUdf.UPPER(name);
dump B;

但当我运行它时，我得到了错误。

java -cp com.bigdata.myUdf.UPPER.jar org.apache.pig.Main -x local /home/hduser/lab/mydata/myscript.pig

错误

Error: Could not find or load main class org.apache.pig.Main

cat.bashrc公司

export PIG_INSTALL=/home/hduser/software/pig
export PATH="${PATH}:${PIG_INSTALL}/bin"
export PIG_CLASSPATH=$HADOOP_CONF_DIR:${PIG_INSTALL}:.
export CLASSPATH=.:${PIG_CLASSPATH}

pig脚本位于：/home/hduser/lab/mydata/myscript.pig
jar文件位于：/home/hduser/software/myudfs/upper.jar
请帮助我理解我做错了什么。提前谢谢。在遵循湿婆沙克提的指示之后。程序运行了，但没有任何输出。

pig -x local myScript.pig

 15/01/05 04:47:57 INFO pig.ExecTypeProvider: Trying ExecType : LOCAL
15/01/05 04:47:57 INFO pig.ExecTypeProvider: Picked LOCAL as the ExecType
2015-01-05 04:47:57,920 [main] INFO  org.apache.pig.Main - Apache Pig version 0.14.0 (r1640057) compiled Nov 16 2014, 18:02:05
2015-01-05 04:47:57,921 [main] INFO  org.apache.pig.Main - Logging error messages to:       /home/hduser/lab/piglog/pig_1420462077918.log
2015-01-05 04:47:57,959 [main] INFO  org.apache.hadoop.conf.Configuration.deprecation - user.name is deprecated. Instead, use mapreduce.job.user.name
2015-01-05 04:47:58,314 [main] INFO  org.apache.hadoop.conf.Configuration.deprecation - fs.default.name is deprecated. Instead, use fs.defaultFS
2015-01-05 04:47:58,315 [main] INFO  org.apache.hadoop.conf.Configuration.deprecation - mapred.job.tracker is deprecated. Instead, use mapreduce.jobtracker.address
2015-01-05 04:47:58,318 [main] INFO  org.apache.pig.backend.hadoop.executionengine.HExecutionEngine - Connecting to hadoop file system at:   file:///
2015-01-05 04:47:58,463 [main] INFO  org.apache.hadoop.conf.Configuration.deprecation -   fs.default.name is deprecated. Instead, use fs.defaultFS
2015-01-05 04:47:59,070 [main] INFO  org.apache.hadoop.conf.Configuration.deprecation - fs.default.name is deprecated. Instead, use fs.defaultFS
2015-01-05 04:47:59,227 [main] INFO  org.apache.pig.Main - Pig script completed in 2 seconds and 505 milliseconds (2505 ms)

Java hadoop mapreduce bigdata apache-pig

来源：https://stackoverflow.com/questions/27768706/pig-error-could-not-find-or-load-main-class-org-apache-pig-main

2条答案

按热度按时间

zd287kbt1#

该错误指示apachejar不在类路径中。 -cp com.bigdata.myUdf.UPPER.jar 不包括必需的jar。它只包括'upper.jar'。您可以在这里查看如何在类路径中正确地包含所有必需的jar
p、我认为您应该使用命令行中的pig命令，而不是按自己的方式执行。但我自己没用过，所以这只是猜测。

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du7egjpx2#

你能按以下步骤做吗？。
1.从下面的链接（pig-0.11.1.jar、hadoop-common-0.21.0.jar和piggybank.jar）下载3个jar文件

http://www.java2s.com/Code/Jar/p/Downloadpig0111jar.htm
http://www.java2s.com/Code/Jar/h/Downloadhadoopcommon0210jar.htm
http://www.java2s.com/Code/Jar/p/Downloadpiggybankjar.htm

2将上述3个jar文件都设置为类路径

export CLASSPATH=/tmp/pig-0.11.1.jar:/tmp/hadoop-common-0.21.0.jar:/tmp/piggybank.jar

三。从当前目录创建目录名“com/bigdata/myudf/”

>>mkdir -p com/bigdata/myUdf/

4编译upper.java文件，确保java\u home设置正确，并且上述三个jars文件都包含在类路径中，否则会出现编译问题

>>javac UPPER.java

5将编译后的upper.class文件移到“com/bigdata/myudf/”文件夹中

>>mv UPPER.class com/bigdata/myUdf/

6创建一个jar文件名upper.jar

>>jar -cvf UPPER.jar com/

7现在将upper.jar包含到pig脚本中并运行以下命令

>>pig -x local myscript.pig

运行上述命令后，您将获得实际输出。
例子
输入

hello
world

myscript.pig文件

REGISTER UPPER.jar; 
std_det = LOAD 'input' USING PigStorage(',') as (name:chararray);
B = FOREACH std_det GENERATE com.bigdata.myUdf.UPPER(name);
dump B;

输出：

(HELLO)
(WORLD)

示例命令：

$ ls
UPPER.java      input   myscript.pig

$ mkdir -p com/bigdata/myUdf/
$ javac UPPER.java
$ mv UPPER.class com/bigdata/myUdf/
$ jar -cvf UPPER.jar com/
$ pig -x local myscript.pig

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pig错误：无法找到或加载主类org.apache.pig.main

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